European astronomers have found the nearest black hole to Earth, according to Associated Press. It is so close that two stars dancing around it can be observed it without a telescope.

The black hole, which is lurking 1,000 light-years from Earth in the southern constellation of Telescopium, belongs to a system with two companion stars that are bright enough to observe with the naked eye. But you won’t be able to see the black hole itself; the massive object has such a strong gravitational pull that nothing — not even light — can escape it.

Astronomers discovered this black hole while studying what they thought was just a binary star system, or two stars that orbit a common center of mass. They were using the MPG/ESO 2.2-meter telescope at the La Silla Observatory in Chile to observe the binary, known as HR 6819, as part of a broader study on double star systems. When they analyzed their observations, the researchers were shocked to learn that a third object was hiding in the system: a black hole. 

“An invisible object with a mass at least 4 times that of the sun can only be a black hole,” Thomas Rivinius, an ESO scientist who led the study, said in a press release. He added, “this system contains the nearest black hole to Earth that we know of.”

The below video shows what the astronomers saw: a star (blue) orbiting an invisible black hole (red), with another star (also blue) orbiting the inner pair. That makes this star system, called HR 6819, a triple system. 

“We were totally surprised when we realized that this is the first stellar system with a black hole that can be seen with the unaided eye,” Petr Hadrava, a scientist at the Academy of Sciences of the Czech Republic in Prague and co-author of the research, said in the release.

The star system is close enough that people in Earth’s southern hemisphere can spot the stars on a clear night.